A combine is an agricultural vehicle used in the harvesting of crops. The combine is typically self-propelled and includes an upper body and a lower support frame, or undercarriage. The upper body has disposed on a forward portion thereof a header assembly and further includes an aft crop processing section and drive mechanism. The drive mechanism typically includes a diesel engine and operator controls which are generally in an enclosed cab. The crop processing section generally includes the combination of a rotating cylinder and concave combination, a series of moving sieves, and a blower arrangement for directing chaff rearward in the combine for discharge therefrom, while allowing the grain to fall under gravity to a lower portion of the combine body. The grain is then displaced upward by means of an elevator for discharge into a storage tank. An off-loading grain auger disposed within the storage tank is typically employed to unload the grain into a transport vehicle such as a truck.
The combine generally includes a pair of forward drive wheels and a pair of aft steerable wheels for turning the combine. The threshing system is disposed immediately aft of the header assembly for receiving the grain and crop residue and allowing the grain to drop downward under the influence of gravity while allowing the separated crop residue to be displaced rearward for discharge from the combine. The threshing system and grain tank are typically disposed intermediate the forward drive wheels and the aft steerable wheels, with the grain tank positioned behind the drive wheels. This arrangement increases the weight on the aft steerable wheels and reduces the weight on the forward drive wheels resulting in reduced drive traction for the combine. This reduced drive traction restricts maneuverability of the combine, particularly in muddy fields, and also limits the combine's grain storage capacity. A large grain storage capacity reduces the frequency of harvested grain off-loading and allows for extended combine operation without interruption for more efficient grain harvesting.
The present invention addresses the aforementioned limitations of the prior art by providing a combine with a movable upper body on a lower support frame which allows for shifting in the weight distribution of the combine to a forward location over tandem drive wheels for improved traction or rearward over the combine's aft steerable wheels to facilitate turning of the combine such as at the end of a field.